U.S. patent application number 12/318811 was filed with the patent office on 2009-07-09 for method of requesting and reporting link quality in an egprs2 system.
Invention is credited to Koo Hyounhee.
Application Number | 20090175227 12/318811 |
Document ID | / |
Family ID | 40844487 |
Filed Date | 2009-07-09 |
United States Patent
Application |
20090175227 |
Kind Code |
A1 |
Hyounhee; Koo |
July 9, 2009 |
Method of requesting and reporting link quality in an EGPRS2
system
Abstract
The link quality reporting method includes measuring link
quality for received radio blocks, and if there is a modulation
scheme with a largest number of radio blocks, reporting link
quality for the modulation scheme, and if there is a plurality of
schemes with the same number of radio blocks, reporting link
quality for a modulation scheme selected using a predetermined
method. Performance deterioration can be minimized in a link
adaptation process.
Inventors: |
Hyounhee; Koo; (Anyang-si,
KR) |
Correspondence
Address: |
MCKENNA LONG & ALDRIDGE LLP
1900 K STREET, NW
WASHINGTON
DC
20006
US
|
Family ID: |
40844487 |
Appl. No.: |
12/318811 |
Filed: |
January 8, 2009 |
Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04L 1/203 20130101;
H04L 1/0026 20130101; H04W 28/18 20130101; H04L 1/0003
20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04W 4/00 20090101
H04W004/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 9, 2008 |
KR |
10-2008-0002624 |
Jan 9, 2008 |
KR |
10-2008-0002625 |
Claims
1. A method of reporting link quality for radio blocks using a
plurality of modulation schemes, the method comprising, performed
in a mobile terminal: determining a link quality parameter for each
modulation scheme and each timeslot assigned to the mobile
terminal; determining the number of times each modulation scheme is
used in each of the assigned timeslots over a reporting period;
selecting at least one modulation scheme; and reporting link
quality information for said selected modulation scheme to a
network, wherein, selecting comprises: selecting the most used
modulation scheme and if there are several mostly used modulation
schemes, selecting one modulation scheme among said mostly used
modulations schemes based on its modulation order or its error
rate.
2. The method of claim 1, wherein selecting one modulation scheme
among said mostly used modulations schemes comprises selecting a
high-order modulation scheme.
3. The method of claim 1, wherein selecting one modulation scheme
among said mostly used modulations schemes comprises selecting a
low-order modulation scheme.
4. The method of claim 1, wherein selecting one modulation scheme
among said mostly used modulations schemes comprises selecting a
modulation scheme with a low mean bit error probability (BEP).
5. The method of claim 1, wherein selecting one modulation scheme
among said mostly used modulations schemes comprises selecting a
modulation scheme with a high mean BEP.
6. The method of claim 1, further comprising selecting another
modulation scheme, wherein said other modulation is the most used
modulation scheme among not selected modulation schemes and if
there are several not selected mostly used modulation schemes,
selecting one modulation scheme among said not selected mostly used
modulation schemes based on its modulation order or its error
rate.
7. The method of claim 6, wherein selecting one modulation scheme
among said not selected mostly used modulations schemes comprises
selecting a high-order modulation scheme.
8. The method of claim 6, wherein selecting one modulation scheme
among said not selected mostly used modulations schemes comprises
selecting a low-order modulation scheme.
9. The method of claim 6, wherein selecting one modulation scheme
among said not selected mostly used modulations schemes comprises
selecting a modulation scheme with a low mean bit error probability
(BEP).
10. The method of claim 6, wherein selecting one modulation scheme
among said not selected mostly used modulations schemes comprises
selecting a modulation scheme with a high mean BEP.
11. The method of claim 1, wherein said link quality information
comprises the link quality parameter for each selected modulation
scheme for each timeslot.
12. The method of claim 1, wherein said link quality information
comprises an averaged value of the link quality parameters of each
selected modulation scheme over several assigned timeslots.
13. The method of claim 1, wherein determining the link quality
parameter comprises: measuring a bit error probability (BEP) per
burst; averaging the measured BEP per radio block; and computing
the link quality parameter based on the measured and averaged BEP
per modulation scheme and per time slot.
14. A mobile terminal comprising a radio frequency (RF) unit
adapted to receive radio blocks using a plurality of modulation
schemes and a processor coupled with the RF unit and adapted for:
determining a link quality parameter for each modulation scheme and
each timeslot assigned to the mobile terminal; determining the
number of times each modulation scheme is used in each of the
assigned timeslots over a reporting period; selecting at least one
modulation scheme; and reporting link quality information for said
selected modulation scheme to a network, wherein, selecting
comprises: selecting the most used modulation scheme and if there
are several mostly used modulation schemes, selecting one
modulation scheme among said mostly used modulations schemes based
on its modulation order or its error rate.
15. The terminal of claim 14, wherein the processor is adapted for
selecting one modulation scheme among said mostly used modulations
schemes comprises selecting a high-order modulation scheme.
16. The terminal of claim 14, wherein the processor is adapted for
selecting one modulation scheme among said mostly used -modulations
schemes comprises selecting a low-order modulation scheme.
17. The terminal of claim 14, wherein the processor is adapted for
selecting one modulation scheme among said mostly used modulations
schemes comprises selecting a modulation scheme with a low mean bit
error probability (BEP).
18. The terminal of claim 14, wherein the processor is adapted for
selecting one modulation scheme among said mostly used modulations
schemes comprises selecting a modulation scheme with a high mean
BEP.
19. The terminal of claim 14, wherein the processor is further
adapted for selecting another modulation scheme, wherein said other
modulation is the most used modulation scheme among not selected
modulation schemes and if there are several not selected mostly
used modulation schemes, selecting one modulation scheme among said
not selected mostly used modulation schemes based on its modulation
order or its error rate.
20. The terminal of claim 19, wherein the processor is adapted for
selecting one modulation scheme among said not selected mostly used
modulations schemes comprises selecting a high-order modulation
scheme.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority of Korean
Patent Application No. 10-2008-0002624 filed on Jan. 9, 2008, and
Korean Patent Application No. 10-2008-0002625 filed on Jan. 9,
2008, which are incorporated by reference in their entirety
herein.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to wireless communications,
and more particularly, to a method of reporting link quality for
radio blocks using various modulation schemes in an enhanced
general packet radio service system (EGPRS) or an enhanced general
packet radio service phase 2 (EGPRS2) system and to a method of
requesting uplink radio resources from a mobile station to a base
station.
[0004] 2. Related Art
[0005] Global system for mobile communication (GSM) is a radio
technology which has been developed as a standardized system for
radio communication systems in Europe and which has widely been
deployed all over the world. General packet radio service (GPRS)
was introduced to provide packet switched data services in circuit
switched data services provided by the GSM. The enhanced data rate
for GSM evolution (EDGE) employs an 8-phase shift keying (PSK) in
addition to the Gaussian minimum shift keying (GMSK) employed in
the GSM. The enhanced general packet radio service (EGPRS)
represents the GPRS using the EDGE.
[0006] A packet data channel (PDCH) denotes a physical channel used
for GPRS/EGPRS traffic. Examples of logical channels mapped onto
the PDCH include a packet common control channel (PCCCH) used for
control signals required in packet transmission initialization, a
packet data traffic channel (PDTCH) for user data, a packet
associated control channel (PACCH) for dedicated signalling, and so
on.
[0007] An enhanced general packet radio service phase 2 (EGPRS2)
supporting further various modulation and coding schemes has
recently being developed. While the EGPRS supports only two
modulation schemes (i.e., GMSK and 8-PSK), the EGPRS2 supports five
modulation schemes (i.e., GMSK, quadrature phase shift keying
(QPSK), 8-PSK, 16-quadrature amplitude modulation (QAM), and
32-QAM). There are two levels of EGPRS2, that is, EGPRS2-A and
EGPRS2-B. The EGPRS2-A supports the GMSK, 8-PSK, 16-QAM, and
32-QAM. The EGPRS2-B supports the GMSK, QPSK, 16-QAM, and 32-QAM. A
downlink EGPRS2-A uses modulation schemes MCS-1 to MCS-4 (MCS
stands for Modulation and Coding Scheme) and DAS-5 to DAS-12 (DAS
stands for Downlink level A modulation and coding Scheme). An
uplink EGPRS2-A uses modulation schemes MCS-1 to MCS-6 and UAS-7 to
UAS-11 (UAS stands for Uplink level A modulation and coding
Scheme). A downlink EGPRS2-B uses modulation schemes MCS-1 to MCS-4
and DBS-5 to DBS-12 (DBS stands for Downlink level B modulation and
coding Scheme). An uplink EGPRS2-B uses modulation schemes MCS-1 to
MCS-4 and UBS-5 to UBS-12 (UBS stands for Uplink level B modulation
and coding Scheme). A modulation and coding scheme for each level
in the EGPRS2 may be found in clause 6.5.5.1.3 of 3GPP TS 43.064
V7.6.0 (2007-08) "Technical Specification; GSM/EDGE Radio Access
Network; General Packet Radio Service (GPRS); Overall description
of the GPRS radio interface; Stage 2 (Release 7)".
[0008] An EGPRS/EGPRS2 system provides a multi-data rate by using
various modulation and coding schemes. For example, data is
transmitted with various data rates through the PDTCH. The data
rate is regulated on the basis of the link quality in a link
adaptation process. If the link quality is good, data is
transmitted with a high data rate. On the contrary, if the link
quality is poor, data is transmitted with a low data rate. Data may
be lost when transmitted according to a modulation and coding
scheme that requires a data rate higher than achievable with the
link quality. In link adaptation, a data throughput is increased
using the highest possible data rate by using a specific modulation
and coding scheme with a predetermined link quality.
[0009] For the link adaptation process, the link quality needs to
be reported from a mobile station (MS) to a base station (BS). In
order for the MS to transmit packet data to a network, uplink radio
resources have to be assigned. As described above, the EGPRS2
supports additional modulation schemes, and the MS supports the two
EGPRS2 levels (i.e., EGPRS2-A and EGPRS2-B).
[0010] In the EGPRS/EGPRS2 system, the link quality between the
base station and the mobile station is represented with a bit error
probability (BEP). The BEP is an expectation value of the actual
bit error rate (BER) of a signal received by the mobile station
through a radio channel. The BEP is measured burst by burst. The
base station selects a suitable modulation and coding scheme
according to the reported link quality.
[0011] The link adaptation can be performed in a most effective
manner when the reported BEP most accurately estimates the actual
BER. With the use of additional modulation schemes in the EGPRS2,
there is a need for a method of effectively reporting link quality
according to the various modulation schemes.
SUMMARY
[0012] The present invention provides a method of reporting link
quality for some of a plurality of modulation schemes in an
enhanced general packet radio service phase 2 (EGPRS2) system using
the plurality of modulation schemes.
[0013] The present invention also provides a method of reporting
link quality to improve performance of a link adaptation process in
an enhanced general packet radio service phase 2 (EGPRS2) system
using a plurality of modulation schemes.
[0014] The present invention also provides a method of requesting
uplink radio resources in an enhanced general packet radio service
phase 2 (EGPRS2) system.
[0015] According to an aspect of the invention, the mobile terminal
reports link quality for radio blocks using a plurality of
modulation schemes by determining a link quality parameter for each
modulation scheme and each timeslot assigned to the mobile
terminal, determining the number of times-each modulation scheme is
used in each of the assigned timeslots over a reporting period,
selecting a modulation scheme per timeslot and reporting to a
network, for each assigned timeslot, the selected modulation scheme
and the corresponding link quality parameter.
[0016] The invention also relates to a corresponding mobile
terminal comprising a radio frequency (RF) unit adapted to receive
radio blocks using a plurality of modulation schemes and a
processor coupled with the RF unit and adapted for determining a
link quality parameter for each modulation scheme and each timeslot
assigned to the mobile terminal, determining the number of times
each modulation scheme is used in each of the assigned timeslots
over a reporting period, selecting a modulation scheme per timeslot
and reporting to a network, for each assigned timeslot, the
selected modulation scheme and the corresponding link quality
parameter.
[0017] Advantageously, the selected modulation scheme is the most
used modulation scheme per timeslot over the reporting period.
[0018] In a specific embodiment the selected modulation scheme is
the modulation scheme with which the mobile terminal has received
the largest number of radio blocks per timeslot over the reporting
period.
[0019] In one embodiment, determining the link quality parameter
comprises measuring a bit error probability (BEP) per burst,
averaging the measured BEP per radio block and computing the link
quality parameter based on the measured and averaged BEP per
modulation scheme and per time slot.
[0020] In one case the plurality of modulation schemes comprises
Gaussian minimum shift keying (GMSK), quadrature phase shift keying
(QPSK), 8-phase shift keying (PSK), 16-quadrature amplitude
modulation (QAM), and 32-QAM.
[0021] Alternatively, the plurality of modulation schemes comprises
GMSK, QPSK, 8-PSK, 16-QAM normal symbol rate (NSR), 16-QAM higher
symbol rate (HSR), 32-QAM NSR, and 32-QAM HSR.
[0022] The invention also relates to a method of reporting link
quality for radio blocks using a plurality of modulation schemes,
the method comprising, performed in a mobile terminal, determining
a link quality parameter for each modulation scheme and each
timeslot assigned to the mobile terminal, determining the number of
times each modulation scheme is used in each of the assigned
timeslots over a reporting period, selecting at least one
modulation scheme and reporting link quality information for said
selected modulation scheme to a network. In this method selecting
comprises selecting the most used modulation scheme and if there
are several mostly used modulation schemes, selecting one
modulation scheme among said mostly used modulations schemes based
on its modulation order or its error rate.
[0023] Similarly, the invention relates to a mobile terminal
comprising a radio frequency (RF) unit adapted to receive radio
blocks using a plurality of modulation schemes and a processor
coupled with the RF unit and adapted for determining a link quality
parameter for each modulation scheme and each timeslot assigned to
the mobile terminal determining the number of times each modulation
scheme is used in each of the assigned timeslots over a reporting
period, selecting at least one modulation scheme and reporting link
quality information for said selected modulation scheme to a
network. In this mobile terminal selecting comprises selecting the
most used modulation scheme and if there are several mostly used
modulation schemes, selecting one modulation scheme among said
mostly used modulations schemes based on its modulation order or
its error rate.
[0024] Advantageously, the invention further comprises selecting
another modulation scheme, wherein said other modulation is the
most used modulation scheme among not selected modulation schemes
and if there are several not selected mostly used modulation
schemes, selecting one modulation scheme among said not selected
mostly used modulation schemes based on its modulation order or its
error rate.
[0025] In one embodiment, selecting one modulation scheme among
said mostly used modulations schemes or said not selected mostly
used modulation schemes comprises selecting a high-order modulation
scheme.
[0026] Alternatively, selecting one modulation scheme among said
mostly used modulations schemes or said not selected mostly used
modulation schemes comprises selecting a low-order modulation
scheme.
[0027] In another alternative selecting one modulation scheme among
said mostly used modulations schemes or said not selected mostly
used modulation schemes comprises selecting a modulation scheme
with a low mean bit error probability (BEP).
[0028] In another alternative wherein selecting one modulation
scheme among said mostly used modulations schemes or said not
selected mostly used modulation schemes comprises selecting a
modulation scheme with a high mean BEP.
[0029] In one embodiment, said link quality information comprises
the link quality parameter for each selected modulation scheme for
each timeslot.
[0030] Alternatively, said link quality information comprises an
averaged value of the link quality parameters of each selected
modulation scheme over several assigned timeslots.
[0031] In one embodiment, determining the link quality parameter
comprises measuring a bit error probability (BEP) per burst,
averaging the measured BEP per radio block and computing the link
quality parameter based on the measured and averaged BEP per
modulation scheme and per time slot.
[0032] Furthermore, the invention also relates to a method of
reporting link quality for radio blocks using a plurality of
modulation schemes, the method comprising, performed in a mobile
terminal: determining a link quality parameter for each modulation
scheme and each timeslot assigned to the mobile terminal,
determining the number of times each modulation scheme is used in
the assigned timeslots over a reporting period, selecting at least
one modulation scheme and reporting to a network the selected
modulation scheme and corresponding link quality information. In
this method, selecting comprises: determining a subset of
modulation schemes among a set of available modulation schemes and
selecting modulation schemes among the sole modulation schemes of
said subset.
[0033] The invention also relates to a corresponding mobile
terminal comprising a radio frequency (RF) unit adapted to receive
radio blocks using a plurality of modulation schemes and a
processor coupled with the RF unit and adapted for: determining a
link quality parameter for each modulation scheme and each timeslot
assigned to the mobile terminal, determining the number of times
each modulation scheme is used in the assigned timeslots over a
reporting period, selecting at least one modulation scheme and
reporting to a network the selected modulation scheme and
corresponding link quality information. In this mobile terminal,
selecting comprises: determining a subset of modulation schemes
among a set of available modulation schemes and selecting
modulation schemes among the sole modulation schemes of said
subset.
[0034] In one embodiment, the set of available modulation schemes
comprises seven modulations schemes and the subset comprises four
modulation schemes.
[0035] Advantageously, the plurality of available modulation
schemes comprise GMSK, QPSK, 8-PSK, 16-QAM normal symbol rate
(NSR), 16-QAM higher symbol rate (HSR), 32-QAM NSR, and 32-QAM
HSR.
[0036] In one embodiment, selecting a modulation scheme comprises
selecting the modulation scheme which is the most used in one
timeslot and among the modulation schemes of the subset.
[0037] Advantageously, said link quality information comprises the
link quality parameter for each selected modulation scheme for each
timeslot.
[0038] Alternatively, said link quality information comprises an
averaged value of the link quality parameters of each selected
modulation scheme over several assigned timeslots.
[0039] In one embodiment, determining the link quality parameter
comprises: measuring a bit error probability (BEP) per burst,
averaging the measured BEP per radio block and computing the link
quality parameter based on the measured and averaged BEP per
modulation scheme and per time slot.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 is a block diagram illustrating a wireless
communication system.
[0041] FIG. 2 is a block diagram illustrating constitutional
elements of a mobile station.
[0042] FIG. 3 shows a concept of a radio block.
[0043] FIGS. 4 and 5 are flow diagrams illustrating a method of
reporting link quality according to two embodiments of the present
invention.
[0044] FIGS. 6 and 7 are flow diagrams illustrating a method of
requesting uplink radio resources according to two embodiments of
the present invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0045] FIG. 1 is a block diagram illustrating a wireless
communication system. This example shows a network based on an
enhanced general packet radio service phase 2 (EGPRS2). Wireless
communication systems are widely used to provide a variety of
communication services of voice, packet data, and so on.
[0046] Referring to FIG. 1, a mobile station (MS) 10 is a
communication instrument carried by a user and may be called using
other terms such as user equipment (UE), a user terminal (UT), and
a subscriber station (SS), a wireless device, etc.
[0047] The communication system also comprises a base station (BS)
20 which includes a base transceiver station (BTS) 22 and a base
station controller (BSC) 24. The BTS 22 communicates with the MS 10
in a cellular area through a radio interface and performs a
synchronization function with the MS 10. The BSC 24 interfaces at
least one BTS 22 with a mobile switching center (MSC) 30. The BS 20
may be called a base station subsystem, a Node-B, or an access
point.
[0048] The MSC 30 connects the BS 20 to a different kind of network
such as a public switching telephone network (PSTN) 65 or a public
land mobile network (PLMN) through a gateway MSC (GMSC) 60. A
visitor location register (VLR) 40 stores temporary user data,
which includes information on the roaming of all the MSs 10 in the
service area of the MSC 30. A home location register (HLR) 50
includes information on all the subscribers in the home network. A
serving GPRS support node (SGSN) 70 takes in charge the management
of the mobility of the subscribers. A gateway GPRS data network
(GGSN) 80 routes a packet at the current position of the MS 10 to
interface the MS with an external packet data network such as a
public data network (PDN) 85.
[0049] A temporary block flow (TBF) is a logical connection offered
by two medium access control (MAC) entities so as to support the
unidirectional transfer of a radio link control (RLC) protocol data
unit (PDU) on basic physical subchannels. The TBF is not provided
in a packet idle mode. At least one TBF is provided in a packet
transfer mode. In the packet transfer mode, radio resources on one
or more packet data physical channels for the transfer of packet
data are assigned to the MS. MAC-idle state means a
MAC-control-entity state where no basic physical subchannel is
assigned. A temporary flow identity (TFI) is assigned to each TBF
by the network. The MS assumes that the TFI value is unique among
concurrent TBFs in the same direction (uplink or downlink) on all
packet data channels (PDCHs) used for the TBFs. The same TFI value
may be used concurrently for TBFs on other PDCHs in the same
direction and for TBFs in the opposite direction.
[0050] A TBF for the GPRS is referred to as a GPRS TBF. A TBF for
the EGPRS is referred to as an EGPRS TBF. A TBF for the EGPRS2 is
referred to as an EGPRS2 TBF. A TBF for the EGPRS2-A is referred to
as an EGPRS2-A TBF. A TBF for the EGPRS2-B is referred to as an
EGPRS2-B TBF.
[0051] FIG. 2 is a block diagram illustrating constitutional
elements of an MS. An MS 50 includes a processor 51, a memory 52, a
radio frequency (RF) unit 53, a display unit 54, and a user
interface unit 55. The memory 52 is coupled to the processor 51 and
stores an MS operating system, applications, and general files. The
display unit 54 displays a variety of information of the MS 50 and
may use well-known elements such as liquid crystal display (LCD),
organic light emitting diode (OLED) display, etc. The user
interface unit 55 can be configured with a combination of
well-known user interfaces such as keypad, touch screen, etc. The
RF unit 53 is coupled to the processor 51 and transmits and/or
receives radio signals.
[0052] The processor 51 measures and reports link quality for radio
blocks received through the RF unit 53. Further, the processor 51
requests the network to assign radio resources for uplink
transmission.
[0053] FIG. 3 shows a concept of a radio block.
[0054] Referring to FIG. 3, one time division multiple access
(TDMA) frame includes 8 timeslots TS0, TS1, . . . , and TS7 in an
EGPRS/EGPRS2 system. The radio block consists of 4 timeslots, each
of which belongs to a different TDMA frame. For example, the radio
block may be configured by selecting the 1.sup.st timeslot TS0 of
each of four consecutive frames. Although the 1.sup.st timeslot TS0
is selected herein, it is also possible to select other timeslots.
This structure of the radio block is exemplary purpose only. The
radio block may be composed of 4 timeslots over 2 TDMA frames.
[0055] A channel, i.e. a timeslot sequence, uses the same timeslot
number in every TDMA frame and is defined by a timeslot number and
a TDMA frame number sequence. A timeslot sequence is regarded as a
timeslot unless there is any explicit different explanation in this
description.
[0056] A mean bit error probability (BEP) (i.e., MEAN_BEP) for one
radio block can be obtained according to Equation 1 below.
MEAN_BEP block = 1 4 i = 1 4 BEP burst i [ Equation 1 ]
##EQU00001##
[0057] In Equation 1, BEP.sub.bursti denotes a BEP for an i.sup.th
burst. A burst denotes information carried on one timeslot. Here,
one timeslot means a single timeslot in one TDMA frame.
[0058] A coefficient of variation of BEP (i.e., CV_BEP) for the
radio block can be obtained according to Equation 2 below.
CV_BEP block = 1 3 k = 1 4 ( BEP burst k - 1 4 i = 1 4 BEP burst i
) 2 1 4 i = 1 4 BEP burst i [ Equation 2 ] ##EQU00002##
[0059] The link quality parameter is obtained by averaging BEPs for
all radio blocks dedicated to an MS with respect to each channel
(timeslot) and each modulation scheme. A reliability R.sub.n of
quality parameters for each modulation scheme is defined as
expressed by Equation 3 below.
R.sub.n=(1-e)R.sub.n-1+ex.sub.n, R.sub.-1=0 [Equation 3]
[0060] In Equation 3, n denotes an iteration index which is
increased for each downlink radio block. The parameter e denotes a
forgetting factor for performing filtering on the MSs. The
forgetting factor e can be determined according to a BEP period
transmitted from the BS. The forgetting factor e can be delivered
to the MS by using a system information message broadcast from the
BS. In some cases an optional parameter is transmitted in dedicated
messages. Depending on which BEP period parameter is used, the
filtering can be the same for all MS or can be specific. The
parameter x.sub.n is a value indicating a presence/absence of a
link quality parameter for an n.sup.th radio block with respect to
each modulation scheme. The value x.sub.n may be `0` or `1`
according to the presence/absence of the link quality
parameter.
[0061] By using the reliability, with respect to radio blocks
having a TFI of the MS itself, the MS obtains the MEAN_BEP and
CV_BEP for each timeslot according to the following equations.
MEAN_BEP _TN n = ( 1 - e x n R n ) MEAN_BEP _TN n - 1 + e x n R n
MEAN_BEP block , n [ Equation 4 ] CV_BEP _TN n = ( 1 - e x n R n )
CV_BEP _TN n - 1 + e x n R n CV_BEP block , n [ Equation 5 ]
##EQU00003##
[0062] Herein, the obtained link quality parameters are for radio
blocks formed using one timeslot per frame. Here, one timeslot
means a single timeslot in one TDMA frame.
[0063] In the EGPRS/EGPRS2 system, a plurality of timeslots can be
assigned to the MS. Thus, for each modulation scheme, the MEAN_BEP
and CV_BEP are obtained by performing an averaging operation over
all channels assigned to the MS (i.e., timeslots for the received
radio blocks having the same TFI as the MS). This averaging is
performed over a reporting period.
MEAN_BEP n = j R n ( j ) MEAN_BEP _TN n ( j ) j R n ( j ) [
Equation 6 ] CV_BEP n = j R n ( j ) CV_BEP _TN n ( j ) j R n ( j )
[ Equation 7 ] ##EQU00004##
[0064] Herein, n denotes an iteration index at the time of
reporting, and j denotes a channel number. When a new cell is
selected or when an MS is entering a packet transfer mode or a
MAC-shared mode, the iteration index n is reset to `0`. If a new
timeslot is assigned for a downlink TBF, then MEAN_BEP_TNn-1,
CV_BEP_TNn-1, and Rn-1 for that timeslot are reset to `0`.
[0065] The MS reports all MEAN_BEPs and CV_BEPs which are
calculated according to Equations 6 and 7 above with respect to
each modulation scheme. Further, according to the request of the
network, the MS can report measurement values for each timeslot,
that is, MEAN_BEP_TN and CV_BEP_TN.
[0066] As described above, in the EGPRS/EGPRS2, the link quality is
measured, calculated and reported for each modulation scheme.
Therefore, if the link quality can be reported for all modulation
schemes used in the EGPRS2, an optimal link adaptation can be
performed. However, reporting of the link quality for all
modulation schemes results in a signalling overhead and thus may
deteriorate the data rate. Moreover, the overhead is too large to
report the link quality for all modulation schemes for every
assigned timeslot.
[0067] According to a current EGPRS/EGPRS2 standard, a packet
downlink assignment message is used as a control message related to
the link quality report. Table 1 below shows a part of the content
of the packet downlink assignment message disclosed in clause
11.2.7 of 3GPP TS 44.060 V7.10.0 (2007-09) "Technical Specification
Group GSM/EDGE Radio Access Network; General Packet Radio Service
(GPRS); Mobile Station (MS)--Base Station System (BSS) interface;
Radio Link Control/Medium Access Control (RLC/MAC) protocol
(Release 7)".
TABLE-US-00001 TABLE 1 < Packet Downlink Assignment message
content > ::= ... { 0 | 1 < EGPRS Window Size : < EGPRS
Window Size IE >> < LINK_QUALITY_MEASUREMENT_MODE : bit
(2) > < EGPRS2_LINK_QUALITY_MEASUREMENT_MODE : bit (1) > {
0 | 1 < BEP_PERIOD2 : bit(4) > } } ...
[0068] In Table 1, the `LINK_QUALITY_MEASUREMENT_MODE` field
determines a measurement value included in `EGPRS Timeslot Link
Quality Measurements Type 2`. The
`EGPRS2_LINK_QUALITY_MEASUREMENT_MODE` field determines a
measurement value included in `EGPRS BEP Link Quality Measurements
Type 2`. The `EGPRS Timeslot Link Quality Measurements Type 2` and
the `EGPRS BEP Link Quality Measurements Type 2` are information
elements (IEs) included in an EGPRS packet downlink
acknowledgement/negative-acknowledgement (Ack/Nack) message. The
EGPRS packet downlink Ack/Nack message indicates a state of a
received RLC data block and is an uplink message transmitted
through a packet associated control channel (PACCH) to report
downlink channel quality.
[0069] The `EGPRS BEP Link Quality Measurements Type 2` includes
information specified using the `EGPRS2 LINK QUALITY MEASUREMENT
MODE` field. If a value of the `EGPRS2 LINK QUALITY MEASUREMENT
MODE` field is `0`, the MS reports MEAN_BEP and CV_BEP for all
modulation schemes used in the received radio blocks by using the
`EGPRS BEP Link Quality Measurements Type 2`. If the value of the
`EGPRS2_LINK_QUALITY_MEASUREMENT_MODE` field is `1`, the MS reports
MEAN_BEP and CV_BEP for two modulation schemes by using the `EGPRS
BEP Link Quality Measurements Type 2`. Table 2 below shows a part
of the content of the `EGPRS BEP Link Quality Measurements Type 2`
disclosed in clause 12.5a.3 of 3GPP TS 44.060 V7.10.0
(2007-09).
TABLE-US-00002 TABLE 2 <EGPRS BEP Link Quality Measurements Type
2 IE> ::= { 0 | 1 < GMSK_MEAN_BEP : bit (5) > <
GMSK_CV_BEP : bit (3) >} { 0 | 1 < 8PSK_MEAN_BEP : bit (5)
> < 8PSK_CV_BEP : bit (3) > } { 0 | 1 < QPSK_MEAN_BEP :
bit (5) > < QPSK_CV_BEP : bit (3) > } { 0 | 1 <
16QAM_MEAN_BEP : bit (5) > < 16QAM_CV_BEP : bit (3) > } {
0 | 1 < 32QAM_MEAN_BEP : bit (5) > < 32QAM_CV_BEP : bit
(3) > };
[0070] The `EGPRS Timeslot Link Quality Measurements Type 2`
includes information specified using the
`LINK_QUALITY_MEASUREMENT_MODE` field. Table 3 below shows a part
of the content of the `EGPRS Timeslot Link Quality Measurements
Type 2` disclosed in clause 12.5a.3 of 3GPP TS 44.060 V7.10.0
(2007-09).
TABLE-US-00003 TABLE 3 <EGPRS Timeslot Link Quality Measurements
Type 2 IE> ::= < BEP Measurement Report Struct > ::= <
Reported_Modulations: bit (3) > { 0 | 1 { 0
<MODULATION_1_MEAN_BEP_TN0 : bit (4) > | 1 <
MODULATION_2_MEAN_BEP_TN0 : bit (4) >}} { 0 | 1 { 0
<MODULATION_1_MEAN_BEP_TN1 : bit (4) > | 1 <
MODULATION_2_MEAN_BEP_TN1 : bit (4) >}} { 0 | 1 { 0
<MODULATION_1_MEAN_BEP_TN2 : bit (4) > | 1 <
MODULATION_2_MEAN_BEP_TN2 : bit (4) >}} { 0 | 1 { 0
<MODULATION_1_MEAN_BEP_TN3 : bit (4) > | 1 <
MODULATION_2_MEAN_BEP_TN3 : bit (4) >}} { 0 | 1 { 0
<MODULATION_1_MEAN_BEP_TN4 : bit (4) > | 1 <
MODULATION_2_MEAN_BEP_TN4 : bit (4) >}} { 0 | 1 { 0
<MODULATION_1_MEAN_BEP_TN5 : bit (4) > | 1 <
MODULATION_2_MEAN_BEP_TN5 : bit (4) >}} { 0 | 1 { 0
<MODULATION_1_MEAN_BEP_TN6 : bit (4) > | 1 <
MODULATION_2_MEAN_BEP_TN6 : bit (4) >}} { 0 | 1 { 0
<MODULATION_1_MEAN_BEP_TN7 : bit (4) > | 1 <
MODULATION_2_MEAN_BEP_TN7 : bit (4) >}};
[0071] The `Reported_Modulations` field indicates for each timeslot
two reported modulation schemes. The MS reports MEAN_BEP for the
most used modulation scheme during a reporting period between the
two modulation schemes specified using the `Reported_Modulations`
field. Table 4 below shows the content of the
`Reported_Modulations` field disclosed in clause 12.5a.3 of the
reference.
TABLE-US-00004 TABLE 4 Reported_Modulations (3 bit field) bit 3 2 1
MODULATION_1 MODULATION_2 For EGPRS2-A: 0 0 0 GMSK 8PSK 0 0 1 GMSK
16QAM 0 1 0 GMSK 32QAM 0 1 1 8PSK 16QAM 1 0 0 8PSK 32QAM 1 0 1
16QAM 32QAM 1 1 0 reserved 1 1 1 reserved For EGPRS2-B: 0 0 0 GMSK
QPSK 0 0 1 GMSK 16QAM 0 1 0 GMSK 32QAM 0 1 1 QPSK 16QAM 1 0 0 QPSK
32QAM 1 0 1 16QAM 32QAM 1 1 0 reserved 1 1 1 reserved
[0072] When the link quality is reported using the `EGPRS Timeslot
Link Quality Measurements Type 2` according to the aforementioned
method, there are several problems as indicated below.
[0073] First, reporting of link quality for a modulation scheme to
be reported may be unsuccessful. For example, it is assumed that an
MS supporting the EGPRS2-A uses `000` as a value for the
`Reported_Modulations` field. That is, for each assigned timeslot,
the MS selects the GMSK and 8-PSK, and reports link quality for the
most used modulation scheme between the GMSK and the 8-PSK. It is
also assumed that timeslots 1, 2, 3, and 5 are assigned to the MS.
According to the conventional method, if the most used modulation
scheme for the timeslots 1, 2, and 5 is the GMSK or 8-PSK and the
most used modulation scheme for the timeslot 3 is the 16-QAM, then
the MS cannot report link quality for the 16-QAM at the timeslot 3
and thus have to report link quality for the GMSK or 8-PSK. This is
because the `Reported_Modulations` field indicates only two
specified modulation schemes. Therefore, if a specific modulation
scheme is more used in one of the assigned timeslots than the
modulation schemes indicated using the `Reported_Modulations`
field, the MS cannot report link quality for the specific
modulation scheme in that timeslot.
[0074] Second, link quality may be reported in a duplication
manner. According to the value of the `EGPRS2 LINK QUALITY
MEASUREMENT MODE` field, the MS reports link quality for all
modulation schemes or for two modulation schemes by using the
`EGPRS BEP Link Quality Measurements Type 2`. The `EGPRS BEP Link
Quality Measurements Type 2` is regularly reported to the network.
The `EGPRS Timeslot Link Quality Measurements Type 2` is
irregularly reported according to the value of the `LINK QUALITY
MEASUREMENT MODE` field. That is, the network is regularly provided
with an average link quality for all assigned timeslots with
respect to all modulation schemes or to two modulation schemes by
using the `EGPRS BEP Link Quality Measurements Type 2`. When
considering unpredictable and variable wireless environment, it is
better for the network to receive many pieces of information
regarding link quality. However, according to the conventional
method of reporting link quality, when the value of the `EGPRS2
LINK QUALITY MEASUREMENT MODE` field is `1`, the network receives
almost duplicated information via the `EGPRS BEP Link Quality
Measurements Type 2` and the `EGPRS Timeslot Link Quality
Measurements Type 2`, unless the MS experiences fast fading. A
difference of the two IEs lies in that one IE includes `per
timeslot MEAN_BEP` and the other IE includes `non-per timeslot
MEAN_BEP`. Thus, the link quality reported using the two IEs can be
regarded as duplicated information.
[0075] Third, link quality may be reported for an unused timeslot.
Assume that timeslots are reconfigured during the reporting period,
and that some timeslots assigned through timeslot reconfiguration
are not the same as timeslots used before timeslot reconfiguration.
According to the conventional method, the MS can consider the use
of one or several timeslots which are no longer used after the
timeslot reconfiguration when two modulation schemes are selected.
As a result, the MS may not be able to correctly report link
quality after timeslot reconfiguration. It is undesirable to
consider the use of the timeslot which is no longer used. The MS
needs to report link quality for currently assigned timeslots.
[0076] Fourth, a link state may not be able to be correctly used.
From the perspective of a statistical analysis, when a sufficiently
large number of samples are used, a representative value is an
average value of the samples. In a wireless environment, there are
numerous factors (i.e., deep fading, scatter, interference, etc,)
that distort an original signal. In an arbitrarily variable
wireless environment, link quality can be useful in the statistical
analysis when a small number of radio blocks is guaranteed for a
reported modulation scheme. According to the conventional method,
modulation schemes indicated using the `Reported_Modulations` field
may not be related to the number of radio blocks in each assigned
timeslot. This means that the number of radio blocks for the
modulation schemes indicated using the `Reported Modulations` field
for each assigned timeslot cannot guarantee the smallest number of
radio blocks required for the effective statistical analysis.
Considering an unnecessary sample that experiences devastating fast
fading due to an instantaneous large obstacle, the influence of the
unnecessary sample cannot be eliminated when an insufficient number
samples are averaged. Therefore, a current link state may not be
appropriately indicated using the reported link quality.
[0077] FIG. 4 is a flow diagram illustrating a method of reporting
link quality according to an embodiment of the present
invention.
[0078] Referring to FIG. 4, in a step S210, a network configures a
link quality report and provides instructions to an MS through a
packet downlink assignment message. To assign a downlink resource
to the MS, the packet downlink assignment message is transmitted on
a packet common control channel (PCCCH) or a packet associated
control channel (PACCH).
[0079] Table 5 below shows an example of an information element
(IE) included in the packet downlink assignment message to
configure the link quality report.
TABLE-US-00005 TABLE 5 < Packet Downlink Assignment message
content > ::= ... { 0 | 1 < EGPRS Window Size : < EGPRS
Window Size IE >> < LINK_QUALITY_MEASUREMENT_MODE : bit
(2) > < EGPRS2_LINK_QUALITY_MEASUREMENT_MODE : bit (1) > {
0 | 1 < BEP_PERIOD2 : bit(4) > } } ...
[0080] Each field of Table 5 above is described in Table 6
below.
TABLE-US-00006 TABLE 6 EGPRS Window Size This information element
defines the window size to be used in an EGPRS TBF. The network
sets the window size according to the number of timeslots assigned
in the direction of the TBF. LINK_QUALITY_MEASUREMENT_MODE (2 bit
field) This field determines the measurements to be included within
the EGPRS Timeslot Link Quality Measurements IE or EGPRS Timeslot
Link Quality Measurements Type 2 IE. bit 2 1 0 0 The MS does not
report either interference measurements (.gamma. values) or per
slot BEP measurements. 0 1 The MS reports available interference
measurements (.gamma. values) for timeslots 0 through 7. The
.gamma. value is defined in 3GPP TS 45.008. No per slot mean BEP
measurements shall be reported. 1 0 The MS reports the mean BEP on
each assigned time slot. In case of EGPRS, the MS reports the mean
BEP measurement corresponding to the modulation for which it has
received a larger number of blocks since the previous report. In
case of EGPRS2, the MS reports both MEAN_BEP_TNx and
REPORTED_MODULATION (see below). The MS makes BEP measurements only
on Radio Blocks intended for it. No interference measurements
(.gamma. values) shall be reported. 1 1 The MS reports the mean BEP
on each assigned time slot. In case of EGPRS, the MS reports the
mean BEP measurement corresponding to the modulation for which it
has received a larger number of blocks since the previous report.
In case of EGPRS2, the MS reports both MEAN_BEP_TNx and
REPORTED_MODULATION (see below). The MS makes BEP measurements only
on Radio Blocks intended for it. In addition to mean BEP, the MS
reports interference measurements (.gamma. values) for no more than
four time slots. If the MS has interference measurements for more
than four timeslots to report, the selection of timeslots for which
measurements are included in each message is implementation
specific, subject to the requirement that a measurement for each
time slot, unless not available (see 3GPP TS 45.008), is included
in at least every other report.
EGPRS2_LINK_QUALITY_MEASUREMENT_MODE (1 bit field) This field
determines the measurements to be included within the EGPRS BEP
Link Quality Measurements Type 2 IE. It is applicable only to MSs
with one or more downlink TBFs using EGPRS2. bit 0 The MS reports
in the EGPRS BEP Link Quality Measurements Type 2 IE the mean_BEP
and CV_BEP for all modulation schemes used on blocks which it has
received since the previous report 1 The MS reports in the EGPRS
BEP Link Quality Measurements Type 2 IE the mean_BEP and CV_BEP for
the two modulation schemes with the highest number of blocks
received since the previous report, unless only one modulation
scheme was used on all blocks received since the previous report,
in which case the mean_BEP and CV_BEP for this modulation scheme
only shall be reported. BEP_PERIOD2 (4 bit field) This field
contains a constant which is used for filtering channel quality
measurements in EGPRS. For details see 3GPP TS 45.008. Range: 0 to
15
[0081] The `LINK_QUALITY_MEASUREMENT_MODE` field is used to
configure a link quality report (i.e., MEAN_BEP_TN and/or
CV_BEP_TN) for each timeslot. The
`EGPRS2_LINK_QUALITY_MEASUREMENT_MODE` field is used to configure
an average link quality report (i.e., MEAN_BEP and/or CV_BEP)
throughout all assigned timeslots. In particular, if a value of the
`LINK_QUALITY_MEASUREMENT_MODE` field is `10` or `11`, the MS
selects the modulation scheme which is the most used in a specific
timeslot within all the assigned timeslots since the last report,
and reports the selected modulation scheme (i.e.,
REPORTED_MODULATION) and link quality (i.e., MEAN_BEP_TNx) for the
selected modulation scheme. In other words, the mobile station
shall report the modulation scheme which has received the largest
number of radio blocks on each currently assigned timeslot as well
as the channel quality parameter for that modulation scheme.
[0082] In a Step 220, the network transmits a radio block to the
MS. The transmission is made in a packet transfer mode.
[0083] In a step 230, the MS determines whether the radio block has
the identifier of the MS itself, that is, the TFI of the MS itself.
While downlink TBF transmission is made, the MS measures received
(Rx) signal quality. The signal quality is measured for the radio
block of a specified MS. According to the TFI, the MS determines
whether the received radio block is dedicated for the MS itself.
For example, when an RLC/MAC data block is transmitted using the
radio block, the MS can confirm the TFI through an RLC/MAC header
since the RLC/MAC header always includes the TFI.
[0084] In a step 240, the MS measures the link quality upon
confirming the TFI. The MS measures the link quality for the radio
blocks including a TFI identical to the TFI assigned to the MS
itself. The signal quality of each channel is measured burst by
burst. A bit error probability (BEP) can be used for measuring link
quality. The BEP includes MEAN_BEP and CV_BEP. The BEP is measured
for all used modulation schemes. For example, if a system supports
Gaussian minimum shift keying (GMSK), 8-phase shift keying (8-PSK),
16-quadrature amplitude modulation (16-QAM), and 32-QAM, then the
MEAN_BEP and CV_BEP are measured for all four modulation
schemes.
[0085] In a step 250, the MS reports to the network the link
quality computed for a modulation scheme to be reported. The MS can
report the link quality through a packet associated control channel
(PACCH) such as by using an EGPRS packet downlink Ack/Nack type 2
message.
[0086] The EGPRS packet downlink Ack/Nack type 2 message indicates
states of received downlink radio blocks, and is used to report a
downlink channel state.
[0087] Table 7 below shows an example of an IE included in the
EGPRS packet downlink Ack/Nack type 2 message.
TABLE-US-00007 TABLE 7 < EGPRS Packet Downlink Ack/Nack Type 2
message content > ::= ... { 0 | 1 < EGPRS Channel Quality
Report Type 2 : < EGPRS Channel Quality Report Type 2 IE >
>} < EGPRS Ack/Nack Description : < EGPRS Ack/Nack
Description IE >> ...
[0088] The `EGPRS Ack/Nack Description` Information Element
includes an RLC parameter indicating an Ack or a Nack for a group
of RLC data blocks.
[0089] An `EGPRS Channel Quality Report Type 2` Information Element
shows downlink quality. An example thereof is shown in Table 8
below.
TABLE-US-00008 TABLE 8 < EGPRS Channel Quality Report Type 2
> ::= < EGPRS BEP Link Quality Measurements Type 2 : <
EGPRS BEP Link Quality Measurements Type 2 IE>> < C_VALUE
: bit (6) > < EGPRS Timeslot Link Quality Measurements Type 2
: <EGPRS Timeslot Link Quality Measurements Type 2 IE >>
;
[0090] The `C_VALUE` field is a normalized Rx signal level in the
MS. The actual value of the `C_VALUE` field can be calculated as
disclosed in clause 10.2.3.1 of the 3GPP TS 45.008 V7.6.0 (2006-11)
"Radio Access Network; Radio subsystem link control (Release
7)".
[0091] The `EGPRS BEP Link Quality Measurements Type 2` Information
Element is used to report an average link quality (i.e., MEAN_BEP
and/or CV_BEP) throughout all assigned timeslots. That is, the
`EGPRS BEP Link Quality Measurements Type 2` Information Element
includes the MEAN_BEP and CV_BEP averaged throughout all timeslots
in the EGPRS2. Table 9 below shows an example of the `EGPRS BEP
Link Quality Measurements Type 2` Information Element.
TABLE-US-00009 TABLE 9 <EGPRS BEP Link Quality Measurements Type
2 IE> ::= { 0 | 1 < GMSK_MEAN_BEP : bit (5) > <
GMSK_CV_BEP : bit (3) >} { 0 | 1 < 8PSK_MEAN_BEP : bit (5)
> < 8PSK_CV_BEP : bit (3) > } { 0 | 1 < QPSK_MEAN_BEP :
bit (5) > < QPSK_CV_BEP : bit (3) > } { 0 | 1 <
16QAM_MEAN_BEP : bit (5) > < 16QAM_CV_BEP : bit (3) > } {
0 | 1 < 32QAM_MEAN_BEP : bit (5) > < 32QAM_CV_BEP : bit
(3) > };
[0092] As indicated above, the EGPRS2 uses five modulation schemes,
that is, GMSK, 8-PSK, QPSK, 16-QAM, and 32-QAM. The `EGPRS BEP Link
Quality Measurements Type 2` Information Element includes MEAN_BEP
and CV_BEP for each modulation scheme.
[0093] The `EGPRS Timeslot Link Quality Measurements Type 2`
Information Element is configured using a `EGPRS2 LINK QUALITY
MEASUREMENT MODE` field, and is used to report link quality for
each assigned timeslot. Table 10 below shows an example of the
`EGPRS Timeslot Link Quality Measurements Type 2` Information
Element.
TABLE-US-00010 TABLE 10 <EGPRS Timeslot Link Quality
Measurements Type 2 IE> ::= { 0 | 1 < BEP_MEASUREMENTS : BEP
Measurement Report Struct >} { 0 | 1 <
INTERFERENCE_MEASUREMENTS : Interference Measurement Report Struct
>}; < BEP Measurement Report Struct > ::= { 0 | 1
<REPORTED_MODULATION : bit (2) > <MEAN_BEP_TN0 : bit (4)
> } { 0 | 1 < REPORTED_MODULATION : bit (2) >
<MEAN_BEP_TN1 : bit (4) > } { 0 | 1 < REPORTED_MODULATION
: bit (2) > <MEAN_BEP_TN2 : bit (4) > } { 0 | 1 <
REPORTED_MODULATION : bit (2) > <MEAN_BEP_TN3 : bit (4) >
} { 0 | 1 < REPORTED_MODULATION : bit (2) > <MEAN_BEP_TN4
: bit (4) > } { 0 | 1 < REPORTED_MODULATION : bit (2) >
<MEAN_BEP_TN5 : bit (4) > } { 0 | 1 < REPORTED_MODULATION
: bit (2) > <MEAN_BEP_TN6 : bit (4) > } { 0 | 1 <
REPORTED_MODULATION : bit (2) > <MEAN_BEP_TN7 : bit (4) >
}; < Interference Measurement Report Struct > ::= { 0 | 1
< I_LEVEL_TN0 : bit (4) > } { 0 | 1 < I_LEVEL_TN1 : bit
(4) > } { 0 | 1 < I_LEVEL_TN2 : bit (4) > } { 0 | 1 <
I_LEVEL_TN3 : bit (4) > } { 0 | 1 < I_LEVEL_TN4 : bit (4)
> } { 0 | 1 < I_LEVEL_TN5 : bit (4) > } { 0 | 1 <
I_LEVEL_TN6 : bit (4) > } { 0 | 1 < I_LEVEL_TN7 : bit (4)
> };
[0094] The `INTERFERENCE_MEASUREMENTS` field includes a value
.gamma. which is calculated from timeslots 0 to 7. This value can
be calculated as disclosed in clause 10.2.3.1 of 3GPP TS 45.008
V7.6.0 (2006-11).
[0095] The `BEP_MEASUREMENTS` struct includes both a modulation
scheme and a link quality which are reported for each assigned
timeslot. A `REPORTED_MODULATION` field indicates the reported
modulation scheme. A `MEAN_BEP_TNn` field indicates MEAN_BEP for an
n.sup.th timeslot with respect to the modulation scheme indicated
using the `REPORTED MODULATION` field. Table 11 shows an example of
the `REPORTED MODULATION` field for EGPRS2-A and EGPRS2-B.
TABLE-US-00011 TABLE 11 REPORTED_MODULATION (2 bit field) The
mobile station shall, for each of its currently assigned timeslots,
report the modulation scheme (indicated using the
REPORTED_MODULATION field) with which it has received the largest
number of blocks since the last report and shall report the
MEAN_BEP_TNx of that modulation scheme. The mapping of the
modulation scheme is as follows. bit 2 1 For EGPRS2-A: 0 0 GMSK 0 1
8PSK 1 0 16QAM 1 1 32QAM For EGPRS2-B: 0 0 GMSK 0 1 QPSK 1 0 16QAM
1 1 32QAM
[0096] According to the proposed method of reporting link quality,
the MS selects a modulation scheme which is the most used in a
specific timeslot within all assigned timeslots since the last
report, and reports the selected modulation scheme and link quality
for the selected modulation scheme. This means that, for each
assigned timeslot, the MS reports a modulation scheme, which is the
most used among the received radio blocks, and link quality of that
modulation scheme. The most used modulation scheme is specified for
each timeslot, and the MS reports the specified modulation scheme
to the network. Therefore, link quality reporting can be flexibly
supported even if a modulation scheme is added or modified in the
EGPRS2 or an evolved system of the EGPRS2. The network can perform
a link adaptation process by determining a modulation and coding
scheme according to the reported link quality.
[0097] The MS can report an accurate link quality for each assigned
timeslot by reporting a link quality for the modulation scheme with
which the largest number of radio blocks is received on each of
assigned timeslots. To avoid reporting duplicated information, the
MS reports a link quality for a modulation scheme in which an
averaging operation is performed throughout all assigned timeslots
by using the `EGPRS BEP Link Quality Measurements Type 2` IE, and
reports a link quality of the most used modulation scheme for each
assigned timeslot by using the `EGPRS Timeslot Link Quality
Measurements Type 2` IE.
[0098] If the network can know the link quality in the uplink radio
resource request operation, radio resources can be effectively
assigned also in the EGPRS2 system. Therefore, performance of the
EGPRS2 system can be improved by allowing the MS to transmit to the
network the link quality for various modulation schemes
additionally supported in the EGPRS2 by using the packet resource
request message.
[0099] The MS reports the link quality of the modulation scheme
with which a largest number of radio blocks are received on each of
currently assigned timeslots, and does not consider the use of a
timeslot which is no longer used. By reporting the link quality of
the modulation scheme for the largest number of radio blocks, a
smallest number of radio blocks can be further surely guaranteed so
that the statistical analysis is useful.
[0100] The MS reports not only the link quality but also the
modulation scheme with which the largest number of radio blocks is
received on each of assigned timeslots. Accordingly, radio
resources can be effectively used, and an overall throughput can be
improved.
[0101] Meanwhile, according to GP-080266 introduced by Nokia in
February of 2008, a technique for multiplexing the EGPRS, EGPRS2-A
and the EGPRS2-B has been proposed. In this technique, three
modulation schemes are added to the EGPRS2-B. That is, the 8-PSK,
16-QAM with normal symbol rate (NSR), and 32-QAM with NSR which are
supported by the EGPRS2-A are added to the GMSK, QPSK, 16-QAM with
higher symbol rate (HSR), and 32-QAM with HSR which are supported
by the conventional EGPRS2-B, so that the EGPRS2-B can support the
GMSK, QPSK, 8-PSK, 16-QAM with NSR, 16-QAM with HSR, 32-QAM with
NSR, and 32-QAM with NSR. The NSR and the HSR use the same
modulation scheme. However, a complex-valued symbol (also referred
to as a modulation symbol) of a modulation scheme with the HSR has
a frequency bandwidth about 1.2 times larger than a complex-valued
symbol of a modulation scheme with the NSR. Since one modulation
scheme supports a higher symbol rate than the other modulation
scheme, the two modulation schemes can be distinguished. For
example, 16-QAM used in the conventional EGPRS2-B has a higher
symbol rate than 16-QAM used in the conventional EGPRS2-A. The
former is referred to as 16-QAM HSR, and the latter is referred to
as 16-QAM NSR.
[0102] When the EGPRS2-A is multiplexed to the EGPRS2-B, the `EGPRS
BEP Link Quality Measurements Type 2` IE described in Table 9 above
can be modified as shown in Table 12 below.
TABLE-US-00012 TABLE 12 <EGPRS BEP Link Quality Measurements
Type 2 IE> ::= { 0 | 1 < GMSK_MEAN_BEP : bit (5) > <
GMSK_CV_BEP : bit (3) >} { 0 | 1 < 8PSK_MEAN_BEP : bit (5)
> < 8PSK_CV_BEP : bit (3) > } { 0 | 1 < QPSK_MEAN_BEP :
bit (5) > < QPSK_CV_BEP : bit (3) > } { 0 | 1 <
16QAM_HSR_MEAN_BEP : bit (5) > < 16QAM_HSR_CV_BEP : bit (3)
> } { 0 | 1 < 32QAM_HSR_MEAN_BEP : bit (5) > <
32QAM_HSR_CV_BEP : bit (3) > } { 0 | 1 < 16QAM_NSR_MEAN_BEP :
bit (5) > < 16QAM_NSR_CV_BEP : bit (3) > } { 0 | 1 <
32QAM_NSR_MEAN_BEP : bit (5) > < 32QAM_NSR_CV_BEP : bit (3)
> };
[0103] In a `BEP_MEASUREMENTS` struct, to support additional
modulation schemes, a `REPORTED_MODULATION` field indicating a
modulation scheme reported for each timeslot may be a 3-bit field
as shown in Table 13 below.
TABLE-US-00013 TABLE 13 REPORTED_MODULATION (3 bit field) bit 3 2 1
For EGPRS2-A: 0 0 0 GMSK 0 0 1 8PSK 0 1 0 16QAM NSR 0 1 1 32QAM NSR
For EGPRS2-B: 0 0 0 GMSK 0 0 1 QPSK 0 1 0 16QAM HSR 0 1 1 16QAM NSR
1 0 0 32QAM HSR 1 0 1 32QAM NSR
[0104] A problem occurs when the number of bits of the
`REPORTED_MODULATION` field is increased to 3 bits only for the
EGPRS2-B. The problem is that a total size of the
`BEP_MEASUREMENTS` struct increases. In addition, in most cases,
the possibility of concurrently using seven modulation schemes
during one reporting period is low. Therefore, the number of bits
of the `REPORTED_MODULATION` field may be set to two bits.
[0105] In a method to be described below, the `REPORTED_MODULATION`
field is set to two bits and is configured by selecting four
modulation schemes from seven modulation schemes used in the
EGPRS2-B. Modulation schemes selected for configuring the
`REPORTED_MODULATION` field are referred to as candidate modulation
schemes. The MS selects the most used modulation scheme from the
candidate modulation schemes, and reports link quality for the
selected modulation scheme. Regarding modulation schemes which were
not selected to configure the `REPORTED_MODULATION` field, link
quality is not reported.
[0106] Table 14 below shows an example of selecting four modulation
schemes other than modulation schemes of the EGPRS2-A to be
multiplexed. This is a case where modulation schemes added for
multiplexing are not frequently used in the EGPRS2-B.
TABLE-US-00014 TABLE 14 REPORTED_MODULATION (2 bit field) bit 2 1
For EGPRS2-A: 0 0 GMSK 0 1 8PSK 1 0 16QAM NSR 1 1 32QAM NSR For
EGPRS2-B: 0 0 GMSK 0 1 QPSK 1 0 16QAM HSR 1 1 32QAM HSR
[0107] Table 15 below shows another example of selecting four
modulation schemes. This is to enable the network to consider a
link quality difference between the HSR and the NSR.
TABLE-US-00015 TABLE 15 REPORTED_MODULATION (2 bit field) bit 2 1
For EGPRS2-A: 0 0 GMSK 0 1 8PSK 1 0 16QAM NSR 1 1 32QAM NSR For
EGPRS2-B: 0 0 16QAM NSR 0 1 16QAM HSR 1 0 32QAM NSR 1 1 32QAM
HSR
[0108] Table 16 below shows another example of selecting four
modulation schemes. Herein, the GMSK is replaced with the 8-PSK.
Since the EGPRS2-B can be used to obtain a higher data rata than
the EGPRS2-A, the GMSK is replaced with the 8-PSK by considering a
possibility of reporting the 8-PSK instead of the GMSK for the
further effective use of resources.
TABLE-US-00016 TABLE 16 REPORTED_MODULATION (2 bit field) bit 2 1
For EGPRS2-A: 0 0 GMSK 0 1 8PSK 1 0 16QAM NSR 1 1 32QAM NSR For
EGPRS2-B: 0 0 QPSK 0 1 8PSK 1 0 16QAM HSR 1 1 32QAM HSR
[0109] With respect to the selected four modulation schemes, the MS
reports, for each assigned timeslots, link quality for the
modulation scheme most used among received radio blocks. The MS
does not report link quality for any modulation scheme other than
the four selected modulation schemes.
[0110] The above examples are for exemplary purposes only, and thus
the four modulation schemes can be selected from the seven
modulation schemes supporting the EGPRS2-B in various combinations.
In addition, the configuration of the `REPORTED_MODULATION` field
may vary from one MS to another or from one time to another.
[0111] Generally speaking, the above examples relates to
determining a subset of modulation schemes among a set of available
modulation schemes and applying the criterion for selecting a
modulation scheme to the sole modulation schemes of the subset.
Depending on the embodiment, the set and the subset can be formed
of any number of modulations schemes. In other words, the MS does
not seem to need to take into account all of 7 modulation schemes
for EGPRS2 channel quality reporting during the reporting
period.
[0112] When the link quality reporting is instructed through the
packet downlink message, the MS can report link quality only for
the most used modulation scheme since the last report. If link
quality is to be reported for two modulation schemes, the MS
reports link quality of the two modulation schemes starting from
the most used modulation scheme. If link quality is to be reported
for three modulation schemes, the MS reports link quality of the
three modulation schemes starting from the most used modulation
scheme. That is, link quality is reported not for all modulation
schemes but for some selected modulation schemes, and thus an
overhead resulted from link quality reporting can be avoided.
[0113] A problem occurs when a plurality of different modulation
schemes have the same number of transmitted radio blocks. That is,
the problem is as to with which condition the MS has to report
channel quality if link quality is to be reported for two
modulation schemes and three or more modulation scheme (e.g., GMSK,
16-QAM, and 32-QAM) have the same number of received radio
blocks.
[0114] In such a situation when there is a plurality of different
modulation schemes with the same number of received radio blocks, a
modulation scheme for reporting link quality can be selected in
various manners. The selection of the modulation scheme may be
predetermined in the MS or may be reported by the network to the
MS.
[0115] According to an embodiment, link quality is reported for two
high-order modulation schemes. For example, if the GMSK, 16-QAM,
and 32-QAM are different modulation schemes with the same number of
most received radio blocks received by the MS, the MS reports link
quality for the 16-QAM and 32-QAM which are higher order modulation
schemes than the GMSK. In other words, for EGPRS2 channel quality
reporting per timeslot, if there are more than one modulation
scheme having the same number and the largest number of blocks on a
currently assigned timeslot, the MS shall report the MEAN_BEP_TNx
for the highest order modulation scheme among those modulation
schemes on that timeslot.
[0116] According to another embodiment, link quality is reported
for two low-order modulation schemes. For example, if the GMSK,
16-QAM, and 32-QAM are different modulation schemes with the same
number of most received radio blocks received by the MS, the MS
reports link quality for the GMSK and 16-QAM.
[0117] According to another embodiment, link quality is reported
for the modulation schemes with the lower MEAN_BEP. For example, if
the GMSK, 16-QAM, and 32-QAM are different modulation schemes with
the number of same most received radio blocks received by the MS
where GMSK_MEAN_BEP is 0.001, 16QAM_MEAN_BEP is 0.003,
32QAM_MEAN_BEP is 0.005, and then link quality is reported for the
GMSK and 16-QAM.
[0118] According to another embodiment, link quality is reported
for a modulation scheme with a higher MEAN_BEP. For example, if the
GMSK, 16-QAM, and 32-QAM are different modulation schemes with the
same number of most received radio blocks received by the MS where
GMSK_MEAN_BEP is 0.001, 16QAM_MEAN_BEP is 0.003, 32QAM_MEAN_BEP is
0.005, and then link quality is reported for the 16-QAM and
32-QAM.
[0119] Depending on the embodiment, the MS may report the link
quality (i.e., MEAN_BEP_TN and CV_BEP_TN) using a timeslot unit,
that is to say per timeslot or may report the average link quality
(i.e., MEAN_BEP and CV_BEP) for a plurality of timeslots, that is
to say throughout all assigned timeslots. The network can perform a
link adaptation process by determining a modulation and coding
scheme according to the reported link quality.
[0120] According to a method of the present invention, link quality
is reported not for all but for some modulation schemes. Therefore,
a signalling overhead is reduced, and performance deterioration is
minimized in a link adaptation process. In addition, even in a case
where there is a plurality of different modulation schemes with the
same number of received radio blocks, an overall system performance
can be increased by defining a modulation scheme whose link quality
is to be reported.
[0121] FIG. 5 is a flow diagram illustrating a method of reporting
link quality according to another embodiment of the present
invention.
[0122] Referring to FIG. 5, in a step S310, a BS transmits a
control message to an MS. The control message includes a specific
signalling `SWITCHING_MODULATION` field for switching a
configuration of a `REPORTED_MODULATION` field. For example, when a
packet downlink assignment message is used as the control message,
the message can be configured as shown in Table 17 below.
TABLE-US-00017 TABLE 17 < Packet Downlink Assignment message
content > ::= ... { 0 | 1 < EGPRS Window Size : < EGPRS
Window Size IE >> < LINK_QUALITY_MEASUREMENT_MODE : bit
(2) > < SWITCHING_MODULATION : bit(1) > <
EGPRS2_LINK_QUALITY_MEASUREMENT_MODE : bit (1) > { 0 | 1 <
BEP_PERIOD2 : bit(4) > } } ...
[0123] As shown in Table 18 below, the `SWITCHING_MODULATION` field
may be included as a part of the `BEP_MEASUREMENTS` struct of the
`EGPRS Timeslot Link Quality Measurements Type 2` IE.
TABLE-US-00018 TABLE 18 <EGPRS Timeslot Link Quality
Measurements Type 2 IE> ::= { 0 | 1 < BEP_MEASUREMENTS : BEP
Measurement Report Struct >} { 0 | 1 <
INTERFERENCE_MEASUREMENTS : Interference Measurement Report Struct
>}; < BEP Measurement Report Struct > ::= <
SWITCHING_MODULATION : bit(1) > { 0 | 1 <REPORTED_MODULATION
: bit (2) > <MEAN_BEP_TN0 : bit (4) > } { 0 | 1 <
REPORTED_MODULATION : bit (2) > <MEAN_BEP_TN1 : bit (4) >
} { 0 | 1 < REPORTED_MODULATION : bit (2) > <MEAN_BEP_TN2
: bit (4) > } { 0 | 1 < REPORTED_MODULATION : bit (2) >
<MEAN_BEP_TN3 : bit (4) > } { 0 | 1 < REPORTED_MODULATION
: bit (2) > <MEAN_BEP_TN4 : bit (4) > } { 0 | 1 <
REPORTED_MODULATION : bit (2) > <MEAN_BEP_TN5 : bit (4) >
} { 0 | 1 < REPORTED_MODULATION : bit (2) > <MEAN_BEP_TN6
: bit (4) > } { 0 | 1 < REPORTED_MODULATION : bit (2) >
<MEAN_BEP_TN7 : bit (4) > }; < Interference Measurement
Report Struct > ::= { 0 | 1 < I_LEVEL_TN0 : bit (4) > } {
0 | 1 < I_LEVEL_TN1 : bit (4) > } { 0 | 1 < I_LEVEL_TN2 :
bit (4) > } { 0 | 1 < I_LEVEL_TN3 : bit (4) > } { 0 | 1
< I_LEVEL_TN4 : bit (4) > } { 0 | 1 < I_LEVEL_TN5 : bit
(4) > } { 0 | 1 < I_LEVEL_TN6 : bit (4) > } { 0 | 1 <
I_LEVEL_TN7 : bit (4) > };
[0124] According to the value of the `SWITCHING_MODULATION` field,
the configuration of the `REPORTED_MODULATION` field can be
switched. For example, when the `SWITCHING_MODULATION` field
consists of one bit, if the value of this field is `0`, the
`REPORTED_MODULATION` field of Table 14 can be used, and if the
value of this field is `1`, the `REPORTED_MODULATION` field of
Table 15 can be used. Alternatively, when the
`SWITCHING_MODULATION` consists of two bits, if the value of the
field is `00`, the `REPORTED_MODULATION` field of Table 14 can be
used, if the value of the field is `01`, the `REPORTED_MODULATION`
field of Table. 15 can be used, and if the value of the field is
`10`, the `REPORTED_MODULATION` field of Table 16 can be used.
[0125] In a step S320, by using the `REPORTED_MODULATION` indicated
using the `SWITCHING_MODULATION` field, the MS selects a modulation
scheme which is the most used in a specific timeslot included in
all assigned timeslots by radio blocks received since the last
report, and reports the selected modulation scheme and link quality
for the selected modulation scheme.
[0126] Now, a method of assigning radio resources for an uplink
packet transmission in an EGPRS/EGPRS2 system will be
described.
[0127] In order to establish an uplink TBF, an MS transmits to a
network a packet channel request message through a packet random
access channel (PRACH) or a random access channel (RACH). There are
two types (i.e., one-phase access and two-phase access) of
operations in uplink TBF establishment.
[0128] The one-phase access is supported only when a radio link
control (RLC) mode is an acknowledge mode. Since a multi-slot class
is also transmitted when the uplink TBF is requested by the MS,
uplink TBF assignment can be achieved without any additional
message between the MS and a network. This means that a multi-slot
assignment is possible starting from an initial stage according to
the configuration of the MS because the network knows the
multi-slot class of the MS which has requested the uplink TBF.
However, a contention may occur in some cases. When a plurality of
MSs transmits (EGPRS/EGPRS2) packet channel request messages
through the same PRACH or RACH, even if TBFs are not assigned to
the MSs, the MSs may perform uplink transmission by considering
that the TBFs are assigned, which results in the contention. To
resolve the contention, the MS transmits a temporary logical link
identifier (TLLI) by appending it to a subsequent RLC data block
through the PDTCH. The TLLI is an MS identifier. If a packet uplink
acknowledgment (ACK)/negative-acknowledgement (NACK) message
received from the network includes the same TLLI, the MS determines
that the resolution of the contention is completed. Thus, in the
subsequent PDTCH, data is transmitted without appending the TLLI.
If the received TLLI is different from the TLLI transmitted by the
MS, the resolution of the contention is determined as a failure,
and thus a TBF release operation is performed.
[0129] FIG. 6 is a flow diagram showing a method of requesting
uplink radio resources according to an embodiment of the present
invention.
[0130] Referring to FIG. 6, in a step S410, an MS transmits an
(EGPRS/EGPRS2) packet channel request message to a network through
a PRACH or a RACH in order to establish an uplink TBF. The
(EGPRS/EGPRS2) packet channel request message includes an access
type indicating either one-phase access or two-phase access and a
parameter required to specify radio resources. The packet channel
request message is transmitted through the PRACH or the RACH using
an access burst. This may be found in clause 11.2.5 of 3GPP TS
44.060 V7.8.0 (2007-03) "Technical Specification Group GSM/EDGE
Radio Access Network; General Packet Radio Service (GPRS); Mobile
Station (MS)--Base Station System (BSS) interface; Radio Link
Control/Medium Access Control (RLC/MAC) protocol (Release 7)". The
EGPRS packet channel request message may be found in clause 11.2.5a
of 3GPP TS 44.060 V7.8.0 (2007-03).
[0131] In a step S420, if the (EGPRS/EGPRS2) packet channel request
message indicates a two-phase access request, the network transmits
a packet uplink assignment message on a packet common control
channel (PCCCH) in order to assign a single radio block on an
uplink PDCH. If the packet channel request message indicates the
two-phase access, the network can assign multi-blocks on the uplink
PDCH.
[0132] In a step S430, upon receiving the packet uplink assignment
message, the MS transmits a packet resource request message in a
radio block assigned using the packet uplink assignment message.
The packet resource request message is a message transmitted on a
packet associated control channel (PACCH) in order to request a
change of the assigned uplink radio resource. The packet resource
request message includes an EGPRS2 link quality and a channel
request description for uplink radio resource assignment. That is,
a link quality for modulation schemes additionally supported in the
EGPRS2 is included in the packet resource request message. Content
of the packet resource request message will be described below.
[0133] When the packet resource request message is transmitted, the
MS starts a resource request timer. The resource request timer is
for evaluating a success or failure of a packet access procedure.
The resource request timer operates for each TBF. Conditions of
starting, stopping, and action at expiry of the resource request
timer is shown in Table 19 below.
TABLE-US-00019 TABLE 19 Resource Request Timer started At sending
the PACKET RESOURCE REQUEST message. A separate instance of the
resource request timer is started for each TBF for which resources
were requested. stopped On receipt of a PACKET UPLINK ASSIGNMENT,
MULTIPLE TBF UPLINK ASSIGNMENT, PACKET TIMESLOT RECONFIGURE or a
MULTIPLE TBF TIMESLOT RECONFIGURE message that assigns resources to
an uplink TBF. On receipt of a PACKET ACCESS REJECT message that
rejects one or more uplink TBFs. action at expiry Reinitiate the
packet access procedure or retransmit the PACKET RESOURCE REQUEST
message.
[0134] In a step S440, as indicated in the dotted line in FIG. 6,
if the MS desires to transmit additional information regarding
radio access capability, the MS can transmit an additional MS radio
access capability message together with an indication of an
`ADDITIONAL MS RAC INFORMATION AVAILABLE` field included in the
packet resource request message.
[0135] In a step S450, in response to the packet resource request
message, the network transmits the packet uplink assignment message
and thus reports the assigned radio resources to the MS. The
network transmits the packet uplink assignment message including a
TLLI of the MS on the PACCH by using the access capability of the
MS. The MS determines a success or failure of a contention
resolution by evaluating the TLLI included in the packet uplink
assignment message.
[0136] Alternatively, instead of transmitting the packet uplink
assignment message, if the packet access of the MS is rejected, the
network may transmit a packet access reject message. Upon receiving
the packet access reject message, the MS stops the resource request
timer and reports a packet access failure to an upper layer.
[0137] Now, a packet resource request message including information
regarding the EGPRS2 link quality will be described. Link quality
for modulation schemes additionally supported in EGPRS2 is
transmitted using the packet resource request message.
[0138] Table 20 below shows an example of an information element
(IE) included in the packet resource request message for the report
of the EGPRS2 link quality.
TABLE-US-00020 TABLE 20 < Packet Resource Request message
content > ::= { 0 | 1 < ACCESS_TYPE : bit (2) > } {0 <
Global TFI : < Global TFI IE > > | 1 < TLLI/ G-RNTI :
< TLLI/ G-RNTI IE > > } < Channel Request Description :
< Channel Request Description IE > > < ADDITIONAL MS
RAC INFORMATION AVAILABLE : bit (1) > ... {0 | 1 < EGPRS BEP
Link Quality Measurements Type 2 : < EGPRS BEP Link Quality
Measurements Type 2 IE>>} { 0 | 1 < EGPRS Timeslot Link
Quality Measurements Type 2 : <EGPRS Tuneslot Link Quality
Measurements Type 2 IE >>} ...
[0139] The `ACCESS_TYPE` field includes a reason of access request.
For example, this field may specify a one or a two-phase access
request, a page response, a cell update, and a mobility management
procedure.
[0140] The `Global TFI` field includes a TFI for the uplink TBF of
the MS. A temporary logical link identity (TLLI) is in association
with a GPRS subscriber, and is defined in 3GPP TS 23.003. A G-RNTI
is defined in 3GPP TS 44.160.
[0141] The `Channel Request Description` IE describes information
necessary to request uplink radio resources. This IE includes
information regarding a radio priority of the requested TBF, an RLC
mode of the requested TBF, an amount of an RLC data block to be
transmitted by the MS, etc.
[0142] The `ADDITIONAL MS RAC INFORMATION AVAILABLE` field
indicates whether to transmit additional information regarding
radio access capability of the MS.
[0143] FIG. 7 is a flow diagram showing a method of requesting
uplink radio resources according to another embodiment of the
present invention.
[0144] This embodiment differs from the embodiment described with
reference to FIG. 6 in that it is initiated by the network
directly.
[0145] Referring to FIG. 7, in a step S510, a network transmits a
packet uplink assignment message to an MS on a PCCCH in order to
instruct transmission of a packet resource request message.
[0146] In a step S520, upon receiving the packet uplink assignment
message, the MS transmits the packet resource request message in a
radio block assigned using the packet uplink assignment message on
a PACCH. The packet resource request message includes an EGPRS2
link quality and a channel request description for uplink radio
resource assignment. Additional details have been described
previously with reference to step S430.
[0147] When the packet resource request message is transmitted, the
MS starts a resource request timer.
[0148] The method then comprises a step S530 performed in a manner
similar with step S440.
[0149] The method further comprises a step S540 performed in a
manner similar with step S450.
[0150] In other words, when a mobile station requests EGPRS2
resources by PACKET RESOURCE REQUEST message, the information on
the link quality measurements is sent if the related IEs are
available and if those IEs would not cause the message to expand
beyond one RLC/MAC control block.
[0151] The IEs and tables described above are for exemplary
purposes only, and thus names of fields included in each IE, the
number of bits of each field, and arrangement of the fields can be
modified.
[0152] According to the present invention, a mobile station can
report link quality for modulation and coding schemes additionally
provided in an enhanced general packet radio service phase 2
(EGPRS2) system. Therefore, the performance of a link adaptation
process can be improved.
[0153] Furthermore, link quality is reported not for all but for
some modulation schemes. Therefore, a signalling overhead is
reduced, and performance deterioration is minimized in a link
adaptation process. In addition, even in a case where there is a
plurality of different modulation schemes with the same number of
received radio blocks, an overall system performance can be
increased by defining a modulation scheme whose link quality is to
be reported.
[0154] Mobile stations can also transmit to a network a link
quality for modulation schemes additionally supported in an
enhanced general packet radio service phase 2 (EGPRS2) system, so
that the network can effectively assign the uplink radio resources
to each mobile station. Therefore, performance of uplink
transmission can be improved.
[0155] The present invention can be implemented with hardware,
software, or combination thereof. Regarding hardware
implementation, the present invention can be implemented with one
of an application specific integrated circuit (ASIC), a digital
signal processor (DSP), a programmable logic device (PLD), a field
programmable gate array (FPGA), a processor, a controller, a
microprocessor, other electronic units, and combination thereof,
which are designed to perform the aforementioned functions.
Regarding software implementation, the present invention can be
implemented with a module for performing the aforementioned
functions. Software is storable in a memory unit and executed by a
processor. Various means widely known to those skilled in the art
can be used as the memory unit or the processor.
[0156] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
spirit and scope of the invention as defined by the appended
claims. The exemplary embodiments should be considered in
descriptive sense only and not for purposes of limitation.
Therefore, the scope of the invention is defined not by the
detailed description of the invention but by the appended claims,
and all differences within the scope will be construed as being
included in the present invention.
* * * * *